Fix FindImageMagick so it works with Ubuntu 15.04
Fix FindImageMagick so it works with Ubuntu 15.04

JohnRThomas/opengl-examples,runewake2/opengl-examples,runewake2/opengl-examples,JohnRThomas/opengl-examples,JohnRThomas/opengl-examples,JohnRThomas/opengl-examples,runewake2/opengl-examples,runewake2/opengl-examples